add webtorrent (websocket) tracker server

This PR merges webtorrent-tracker into this repo. Keeping the code in
sync between the two repos was becoming burdensome. This change should
not effect performance of the server since the webtorrent tracker is
disabled by default.

To enable the webtorrent tracker (disabled by default), do:

```js
var server = new Server({ ws: true })
```

Author: feross

client.js

@@ -14,7 +14,9 @@ var WebSocketTracker = require('./lib/websocket-tracker')
 inherits(Client, EventEmitter)
 
 /**
- * A Client manages tracker connections for a torrent.
+ * BitTorrent tracker client.
+ *
+ * Find torrent peers, to help a torrent client participate in a torrent swarm.
  *
  * @param {string} peerId          peer id
  * @param {Number} port            torrent client listening port

lib/parse_http.js

@@ -4,18 +4,19 @@ var common = require('./common')
 
 var REMOVE_IPV4_MAPPED_IPV6_RE = /^::ffff:/
 
-function parseHttpRequest (req, options) {
-  options = options || {}
+function parseHttpRequest (req, opts) {
+  if (!opts) opts = {}
   var s = req.url.split('?')
   var params = common.querystringParse(s[1])
 
-  if (options.action === 'announce' || s[0] === '/announce') {
+  if (opts.action === 'announce' || s[0] === '/announce') {
     params.action = common.ACTIONS.ANNOUNCE
 
     if (typeof params.info_hash !== 'string' || params.info_hash.length !== 20) {
       throw new Error('invalid info_hash')
     }
     params.info_hash = common.binaryToHex(params.info_hash)
+
     if (typeof params.peer_id !== 'string' || params.peer_id.length !== 20) {
       throw new Error('invalid peer_id')
     }
@@ -24,18 +25,18 @@ function parseHttpRequest (req, options) {
     params.port = Number(params.port)
     if (!params.port) throw new Error('invalid port')
 
-    params.left = Number(params.left)
-    params.compact = Number(params.compact)
+    params.left = Number(params.left) || Infinity
+    params.compact = Number(params.compact) || 0
     params.numwant = Math.min(
       Number(params.numwant) || common.DEFAULT_ANNOUNCE_PEERS,
       common.MAX_ANNOUNCE_PEERS
     )
 
-    params.ip = options.trustProxy
+    params.ip = opts.trustProxy
       ? req.headers['x-forwarded-for'] || req.connection.remoteAddress
       : req.connection.remoteAddress.replace(REMOVE_IPV4_MAPPED_IPV6_RE, '') // force ipv4
     params.addr = (common.IPV6_RE.test(params.ip) ? '[' + params.ip + ']' : params.ip) + ':' + params.port
-  } else if (options.action === 'scrape' || s[0] === '/scrape') {
+  } else if (opts.action === 'scrape' || s[0] === '/scrape') {
     params.action = common.ACTIONS.SCRAPE
     if (typeof params.info_hash === 'string') params.info_hash = [ params.info_hash ]
 
@@ -48,7 +49,7 @@ function parseHttpRequest (req, options) {
       })
     }
   } else {
-    throw new Error('Invalid action in HTTP request: ' + params.action)
+    throw new Error('invalid action in HTTP request: ' + params.action)
   }
 
   return params

lib/parse_websocket.js

@@ -0,0 +1,33 @@
+module.exports = parseWebSocketRequest
+
+var common = require('./common')
+
+function parseWebSocketRequest (socket, params) {
+  params = JSON.parse(params) // may throw
+
+  params.action = common.ACTIONS.ANNOUNCE
+  params.socket = socket
+
+  if (typeof params.info_hash !== 'string' || params.info_hash.length !== 20) {
+    throw new Error('invalid info_hash')
+  }
+  params.info_hash = common.binaryToHex(params.info_hash)
+
+  if (typeof params.peer_id !== 'string' || params.peer_id.length !== 20) {
+    throw new Error('invalid peer_id')
+  }
+  params.peer_id = common.binaryToHex(params.peer_id)
+
+  if (params.answer &&
+      (typeof params.to_peer_id !== 'string' || params.to_peer_id.length !== 20)) {
+    throw new Error('invalid `to_peer_id` (required with `answer`)')
+  }
+
+  params.left = Number(params.left) || Infinity
+  params.numwant = Math.min(
+    Number(params.offers && params.offers.length) || 0, // no default - explicit only
+    common.MAX_ANNOUNCE_PEERS
+  )
+
+  return params
+}

lib/swarm.js

@@ -12,7 +12,7 @@ function Swarm (infoHash, server) {
 
 Swarm.prototype.announce = function (params, cb) {
   var self = this
-  var peer = self.peers[params.addr]
+  var peer = self.peers[params.addr || params.peer_id]
 
   // Dispatch announce event
   var fn = '_onAnnounce_' + params.event
@@ -24,13 +24,20 @@ Swarm.prototype.announce = function (params, cb) {
     cb(null, {
       complete: self.complete,
       incomplete: self.incomplete,
-      peers: self._getPeers(params.numwant)
+      peers: self._getPeers(params.numwant, params.peer_id)
     })
   } else {
     cb(new Error('invalid event'))
   }
 }
 
+Swarm.prototype.scrape = function (params, cb) {
+  cb(null, {
+    complete: this.complete,
+    incomplete: this.incomplete
+  })
+}
+
 Swarm.prototype._onAnnounce_started = function (params, peer) {
   if (peer) {
     debug('unexpected `started` event from peer that is already in swarm')
@@ -39,11 +46,12 @@ Swarm.prototype._onAnnounce_started = function (params, peer) {
 
   if (params.left === 0) this.complete += 1
   else this.incomplete += 1
-  peer = this.peers[params.addr] = {
-    ip: params.ip,
-    port: params.port,
+  peer = this.peers[params.addr || params.peer_id] = {
+    complete: false,
+    ip: params.ip, // only http+udp
     peerId: params.peer_id,
-    complete: false
+    port: params.port, // only http+udp
+    socket: params.socket // only websocket
   }
 }
 
@@ -55,7 +63,7 @@ Swarm.prototype._onAnnounce_stopped = function (params, peer) {
 
   if (peer.complete) this.complete -= 1
   else this.incomplete -= 1
-  this.peers[params.addr] = null
+  this.peers[params.addr || params.peer_id] = null
 }
 
 Swarm.prototype._onAnnounce_completed = function (params, peer) {
@@ -80,24 +88,16 @@ Swarm.prototype._onAnnounce_update = function (params, peer) {
   }
 }
 
-Swarm.prototype._getPeers = function (numwant) {
+// TODO: randomize the peers that are given out
+Swarm.prototype._getPeers = function (numWant, fromPeerId) {
   var peers = []
   for (var peerId in this.peers) {
-    if (peers.length >= numwant) break
+    if (peers.length >= numWant) break
+    if (peerId === fromPeerId) continue // skip self
+
     var peer = this.peers[peerId]
     if (!peer) continue // ignore null values
-    peers.push({
-      'peer id': peer.peerId,
-      ip: peer.ip,
-      port: peer.port
-    })
+    peers.push(peer)
   }
   return peers
 }
-
-Swarm.prototype.scrape = function (params, cb) {
-  cb(null, {
-    complete: this.complete,
-    incomplete: this.incomplete
-  })
-}

package.json

@@ -35,6 +35,7 @@
     "simple-peer": "4.0.4",
     "simple-websocket": "1.0.4",
     "string2compact": "^1.1.1",
+    "ws": "^0.7.1",
     "xtend": "4.0.0"
   },
   "devDependencies": {